Why are my Vitamin D levels not improving?

I'm 16 years old and was told in November that I have a Vitamin D deficiency. My level was 18. He put me on 50,000 iU a week for 4 months. They kept acting surprised when I said my fatigue wasn't improving. Several months later they tested my levels again and it only went up to 23. Now I'm back on 50,000 iU for 12 weeks and I'm supposed to take a D3 supplement. Is it normal that my level did not go up that much? And why didn't it go up more?

The first thing that pops into my head when you mention that is "celiac diseases".
People with conditions like celiac disease, Gluten Sensitivity, IBS and Crohn's Disease will likely be Vitamin D Deficient unless they take large amounts of Vitamin D or get a lot of sun.
You will probably need a blood test,just to make sure.
2-Vitamin D is one of the fat soluble vitamins. That means that fat is required for it to be absorbed through the stomach,Simply take walnut or peanut butter or avocado or any other healthy fat when you take your Vit D3.
3-magnesium is required in order for Vitamin D to be converted into its active form in the blood. So if you are magnesium deficient then you will likely have difficulty converting the Vitamin D into a usable form in your body.

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